Species Of Lysobacter Research Articles

Genome sequencing and mining expand the naturalproduct repertoire of Lysobacter.

Compounds produced by living organisms serve as an important source of inspiration for the development of pharmaceuticals. A potential source of new natural products are bacteria from a genus with species that are known to produce bioactive natural products, but are relatively understudied. Lysobacter is a genus of bacteria that have attracted attention as possible biocontrol agents and are known to produce antibiotic natural products. To further explore the biosynthetic potential of Lysobacter, we sequenced the genomes of two species and performed genome mining studies on those and publicly available genomes. In this study we produced draft genome sequences for Lysobacter firmicutimachus and Lysobacter yananisis. We additionally examined 113 publicly available Lysobacter genomes and found that biosynthetic potential of individual species ranges broadly, with species having between 1 and nearly 20 biosynthetic gene clusters. Filtering for more complete genome assemblies and 9 or more biosynthetic gene clusters, we performed genome mining on 24 Lysobacter genomes. Within these genomes we identified 21 unique nonribosomal peptide, 11 unique hybrid polyketide/nonribosomal peptide, 4 unique polyketide, and 27 unique lanthipeptide biosynthetic gene clusters that produce uncharacterized compounds. Additionally, we tentatively identified the biosynthetic gene cluster in L. rmicutimachus responsible for producing plusbacins, which has not been previously identified. This study demonstrated that Lysobacter have a large repertoire of natural products that remain to be characterized. Additionally, we found that some Lysobacter species are substantially more biosynthetically gifted than others and that strains of the same species of Lysobacter have similar biosynthetic capacities.

Lysobacter stagni sp. nov. and Limnohabitans lacus sp. nov., isolated from a pond.

Two Gram-negative bacteria, designated as strains LF1T and HM2-2T, were isolated from an artificial pond in a honey farm at Hoengseong-gun, Gangwon-do, Republic of Korea. The 16S rRNA sequence analysis results revealed that strain LF1T belonged to the genus Lysobacter and had the highest sequence similarity to Lysobacter niastensis GH41-7T (99.0 %), Lysobacter panacisoli CJ29T (98.9 %), and Lysobacter prati SYSU H10001T (98.2 %). Its growth occurred at 20-37 °C, at pH 5.0-12.0, and in the presence of 0-2% NaCl. The major fatty acids were iso-C15 : 0, iso-C16 : 0, and summed feature 9 (iso-C17 : 1 ω9c and/or C16 : 0 10-methyl). The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol. The DNA G+C content was 67.5 mol%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain LF1T and species of the genus Lysobacter were 79.1-84.4% and 22.0-27.5 %, respectively. The 16S rRNA sequence analysis results revealed that strain HM2-2T belonged to the genus Limnohabitans and was most closely related to Limnohabitans planktonicus II-D5T (98.9 %), Limnohabitans radicicola JUR4T (98.4%), and Limnohabitans parvus II-B4T (98.4 %). Its growth occurred at 10-35 °C, at pH 5.0-11.0, and in the presence of 0-2% NaCl. The major fatty acids were C16 : 0 and summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c). The major polar lipid was phosphatidylethanolamine. The DNA G+C content was 59.9 mol%. The ANI and dDDH values between strain HM2-2T and its closely related strains were 75.1-83.0% and 20.4-26.4 %, respectively. Phenotypic, genomic, and phylogenetic data revealed that strains LF1T and HM2-2T represent novel species in the genera Lysobacter and Limnohabitans, for which the names Lysobacter stagni sp. nov. and Limnohabitans lacus sp. nov. are proposed, respectively. The type strain of Lys. stagni is LF1T (=KACC 23251T=TBRC 17648T), and that of Lim. lacus is HM2-2T (=KACC 23250T=TBRC 17649T).

A unique role of the pyrimidine de novo synthesis enzyme ODCase in Lysobacter enzymogenes

Bacterial species of the genus Lysobacter are environmentally ubiquitous with strong antifungal biocontrol potential. Heat-stable antifungal factor (HSAF) secreted by the biocontrol bacterium Lysobacter enzymogenes OH11 has broad-spectrum and highly efficient antifungal activity. Studying the biosynthetic regulations of HSAF would lay an important foundation for strain engineering toward improved HSAF production. In this work, we demonstrate that Le0752, an orotidine-5´-phosphate decarboxylase enzyme (ODCase) catalyzing a pivotal step of the UMP de novo biosynthesis pathway, is vital for HSAF-mediated antimicrobial activities and growth of L. enzymogenes OH11, but not for twitching motility. This gene regulates the production of HSAF by affecting the expression of lafB, a key gene in the HSAF biosynthesis operon, through the transcription factor Clp. Interestingly, bioinformatics analysis revealed that Le0752 belongs to the Group III ODCases, whereas its homologs in the closely related genera Xanthomonas and Stenotrophomonas belong to Group I, which contains most ODCases from Gram-positive bacteria, Gram-negative bacteria and cyanobacteria. Moreover, the Group I ODCase PXO_3614 from the Xanthomonas oryzae pv. oryzae PXO99A strain complemented the Le0752 mutant in regulating HSAF-mediated antagonistic activity. Together, these results highlight the important requirement of de novo pyrimidine biosynthetic enzymes for antibiotic HSAF production in L. enzymogenes, which lays an important foundation for improving HSAF production via metabolic flow design and for dissecting the regulatory functions of bacterial ODCases.

Lysobacter arvi sp. nov. Isolated from Farmland Soil.

A bacterial strain designated as UC was isolated from farmland soil. Strain UCT formed a pale yellow colony on nutrient agar. Cell morphology revealed it as the rod-shaped bacterium that stained Gram-negative. The 16S rRNA gene sequence analysis identified strain UCT as a member of the genus Lysobacter that showed high identity with L. soli DCY21T (99.5%), L. panacisoli CJ29T (98.7%), and L. tabacisoli C8-1T (97.9%). It formed a distinct cluster with these strains in the neighbor-joining phylogenetic tree. A similar tree topology was observed in TYGS-based phylogenomic analysis. However, genome sequence analyses of strain UCT showed 87.7% average nucleotide identity and 34.7% digital DNA-DNA hybridization similarity with the phylogenetically closest species, L. soli DCY21T. The similarity was much less with other closely related strains of the genus Lysobacter. The G + C content of strain UCT was 68.1%. Major cellular fatty acids observed were C14:0 iso (13.4%), C15:0 iso (13.6%), and C15:0 anteiso (14.8%). Quinone Q-8 was the major respiratory ubiquinone. Predominant polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, and phosphatidylglycerol. Production of xanthomonadin pigment was observed. Based on phenotypic differences and phylogenomic analysis, strain UCT represents a novel species of the genus Lysobacter, for which the name Lysobacter arvi is proposed. The type strain of the novel species is UCT (= KCTC 92613T = JCM 23757T = MTCC 12824T).

Genetic Basis and Expression Pattern Indicate the Biocontrol Potential and Soil Adaption of Lysobacter capsici CK09.

Lysobacter species have attracted increasing attention in recent years due to their capacities to produce diverse secondary metabolites against phytopathogens. In this research, we analyzed the genomic and transcriptomic patterns of Lysobacter capsici CK09. Our data showed that L. capsici CK09 harbored various contact-independent biocontrol traits, such as fungal cell wall lytic enzymes and HSAF/WAP-8294A2 biosynthesis, as well as several contact-dependent machineries, including type 2/4/6 secretion systems. Additionally, a variety of hydrolytic enzymes, particularly extracellular enzymes, were found in the L. capsici CK09 genome and predicted to improve its adaption in soil. Furthermore, several systems, including type 4 pili, type 3 secretion system and polysaccharide biosynthesis, can provide a selective advantage to L. capsici CK09, enabling the species to live on the surface in soil. The expression of these genes was then confirmed via transcriptomic analysis, indicating the activities of these genes. Collectively, our research provides a comprehensive understanding of the biocontrol potential and soil adaption of L. capsici CK09 and implies the potential of this strain for application in the future.

Lysobacter changpingensis sp. nov., a novel species of the genus Lysobacter isolated from a rhizosphere soil of strawberry in China

In the present work, we characterized in detail strain CM-3-T8T, which was isolated from the rhizosphere soil of strawberries in Beijing, China, in order to elucidate its taxonomic position. Cells of strain CM-3-T8T were Gram-negative, non-spore-forming, aerobic, short rod. Growth occurred at 25–37 °C, pH 5.0–10.0, and in the presence of 0–8% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CM-3-T8T formed a stable clade with Lysobacter soli DCY21T and Lysobacter panacisoli CJ29T, with the 16S rRNA gene sequence similarities of 98.91% and 98.50%. The average nucleotide identity and digital DNA-DNA hybridization values between strain SG-8 T and the two reference type strains listed above were 76.3%, 79.6%, and 34.3%, 27%, respectively. The DNA G + C content was 68.4% (mol/mol). The major cellular fatty acids were comprised of C15:0 iso (36.15%), C17:0 iso (8.40%), and C11:0 iso 3OH (8.28%). The major quinone system was ubiquinone Q-8. The major polar lipids were phosphatidylethanolamine (PE), phosphatidylethanolamine (PME), diphosphatidylglycerol (DPG), and aminophospholipid (APL). On the basis of phenotypic, genotypic, and phylogenetic evidence, strain CM-3-T8T (= ACCC 61714 T = JCM 34576 T) represents a new species within the genus Lysobacter, for which the name Lysobacter changpingensis sp. nov. is proposed.

Loss of Flagella-Related Genes Enables a Nonflagellated, Fungal-Predating Bacterium To Strengthen the Synthesis of an Antifungal Weapon.

Loss of flagellar genes causes a nonmotile phenotype. The genus Lysobacter consists of numerous environmentally ubiquitous, nonflagellated bacteria, including Lysobacter enzymogenes, an antifungal bacterium that is beneficial to plants. L. enzymogenes still has many flagellar genes on its genome, although this bacterium does not engage in flagella-driven motility. Here, we report that loss of certain flagellar genes allows L. enzymogenes to strengthen its evolutionarily gained capacity in fungal killing. To clarify why this bacterium loses flagellar genes during the evolutionary process, we cloned several representative flagellar genes from Xanthomonas oryzae, a flagellated, phylogenetically related species of Lysobacter, and introduced them individually into L. enzymogenes to mimic genomic reacquisition of lost flagellar genes. Heterogeneous expression of the three X. oryzae flagellar structural genes (Xo-motA, Xo-motB, Xo-fliE) and one flagellar regulatory gene (Xo-fleQ) remarkably weakened the bacterial capacity to kill fungal pathogens by impairing the synthesis of an antifungal weapon, known as the heat-stable antifungal factor (HSAF). We further investigated the underlying mechanism by selecting Xo-FleQ as the representative because it is a master transcription factor responsible for flagellar gene expression. Xo-FleQ inhibited the transcription of operon genes responsible for HSAF synthesis via direct binding of Xo-FleQ to the promoter region, thereby decreasing HSAF biosynthesis by L. enzymogenes. These observations suggest a possible genome and function coevolution event, in which an antifungal bacterium deletes certain flagellar genes in order to enhance its ability to kill fungi. IMPORTANCE It is generally recognized that flagellar genes are commonly responsible for the flagella-driven bacterial motility. Thus, finding nonflagellated bacteria partially or fully lost flagellar genes is not a surprise. However, the present study provides new insights into this common idea. We found that loss of either certain flagellar structural or regulatory genes (such as motA, motB, fliE, and fleQ) allows a nonflagellated, antifungal bacterium (L. enzymogenes) to stimulate its fungal-killing capacity, outlining a genome-function coevolution event, where an antifungal bacterium "smartly" designed its genome to "delete" crucial flagellar genes to coordinate flagellar loss and fungal predation. This unusual finding might trigger bacteriologists to reconsider previously ignored functions of the lost flagellar genes in any nonflagellated, pathogenic, or beneficial bacteria.

Lysobacter lactosilyticus sp. nov., a Novel β-Galactosidase Producing Bacterial Strain Isolated from Farmland Soil Applied with Amino Acid Fertilizer.

To isolate β-galactosidase producing bacterial resources, a novel Gram-stain-negative, strictly aerobic bacterial strain designated as A6T was obtained from a farmland soil sample. Cells of the strain were rod-shaped (0.4-0.7μm × 1.8-2.2μm) without flagella and motility. Strain A6T grew optimally at 30 °C, pH 7.0 with 0% (w/v) NaCl. Based on phylogenetic analysis, strain A6T clustered within the genus Lysobacter clade and branched with Lysobacter dokdonensis KCTC 12822T (99.5%, 16S rRNA gene sequence similarity) and Lysobacter caseinilyticus KACC 19816T (98.5%). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain A6T and Lysobacter dokdonensis KCTC 12822T were 82.7% and 26.2%, and the values for strain A6T and KACC 19816T were 81.4% and 23.8%, respectively. Iso-C16:0, iso-C15:0, summed feature 9 (C17:1 iso ω9c and/or C16:0 10-methyl) and summed feature 3 (C16:1ω7c and/or C16:1 ω6c) were the major fatty acids, diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine were the major polar lipids, and ubiquinone 8 (Q-8) was the major ubiquinone. The genomic DNA G+C content was 67.2mol%. Furthermore, under the condition of 30 °C, pH 7.0, 4% inoculation with 10.0gL-1 lactose, the β-galactosidase activity produced by strain A6T was highest, reaching 95.3 UmL-1, indicating that this strain could be applied as a potential strain for β-galactosidase production. Strain A6T represents a novel species of the genus Lysobacter, and Lysobacter lactosilyticus sp. nov. is proposed on the basis of phenotypic, genotypic, and chemotaxonomic analysis. The type strain is A6T (=KCTC 82184T=CGMCC 1.18582T).

Lysobacter sedimenti sp. nov., Isolated from the Sediment, and Reclassification of Luteimonas lumbrici as Lysobacter lumbrici comb. nov.

A bacterium, designated 50T was isolated from the sediment of a pesticide plant in Shandong Province, PR China. The strain was non-motile, Gram stain-negative, rod shaped and grew optimally on NA medium at 30°C, pH 7.5 and with 0% (w/v) NaCl. Strain 50T showed the highest 16S rRNA gene sequence similarity with Lysobacter pocheonensis Gsoil 193T (96.7%), followed by Luteimonas lumbrici 1.1416T (96.5%). Phylogenetic analyses based on 16S rRNA indicated that strain 50T and Luteimonas lumbrici 1.1416T were clustered with the genus of Lysobacter and formed a subclade with Lysobacter pocheonensis Gsoil 193T. In the phylogenetic analysis based on the genome sequences, strain 50T and Luteimonas lumbrici 1.1416T were also clustered with the type strains of the genus Lysobacter. The obtained ANI and the dDDH value between 50T and Luteimonas lumbrici 1.1416T were 80.6% and 24.0%, respectively. The respiratory quinone was ubiquinone-8 (Q-8), and the major cellular fatty acids were iso-C15: 0 (31.7%), summed feature 9 (iso-C17:1 ω9c or C16:0 10-methyl) (23.7%), iso-C17:0 (14.3%) and iso-C16:0 (12.6%). The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and unidentified aminophospholipid, unidentified phospholipid and unidentified lipid. The genomic DNA G + C content was 69.5mol%. According to the phenotypic, chemotaxonomic and phylogenetic analyses, strain 50T represents a novel species of the genus Lysobacter, for which the name Lysobacter sedimenti sp. nov. is proposed, with strain 50T (= KCTC 92088T = CCTCC AB 2022035T) as the type strain. In this study, it is also proposed that Luteimonas lumbrici should be transferred to the genus Lysobacter as Lysobacter lumbrici comb. nov. The type strain of Lysobacter lumbrici is 1.1416T (= KCTC 62979T = CCTCC AB 2018348T).

Parvicella tangerina gen. nov., sp. nov. (Parvicellaceae fam. nov., Flavobacteriales), first cultured representative of the marine clade UBA10066, and Lysobacter luteus sp. nov., from activated sludge of a seawater-processing wastewater treatment plant.

Two strains isolated from a sample of activated sludge that was obtained from a seawater-based wastewater treatment plant on the southeastern Mediterranean coast of Spain have been characterized to achieve their taxonomic classification, since preliminary data suggested they could represent novel taxa. Given the uniqueness of this habitat, as this sort of plants are rare in the world and this one used seawater to process an influent containing intermediate products from amoxicillin synthesis, we also explored their ecology and the annotations of their genomic sequences. Analysis of their 16S rRNA gene sequences revealed that one of them, which was orange-pigmented, was distantly related to Vicingus serpentipes (family Vicingaceae) and to other representatives of neighbouring families in the order Flavobacteriales (class Flavobacteriia) by 88-89 % similarities; while the other strain, which was yellow-pigmented, was a putative new species of Lysobacter (family Xanthomonadaceae, order Xanthomonadales, class Gammaproteobacteria) with Lysobacter arseniciresistens as closest relative (97.3 % 16S rRNA sequence similarity to its type strain). Following a polyphasic taxonomic approach, including a genome-based phylogenetic analysis and a thorough phenotypic characterization, we propose the following novel taxa: Parvicella tangerina gen. nov., sp. nov. (whose type strain is AS29M-1T=CECT 30217T=LMG 32344T), Parvicellaceae fam. nov. (whose type genus is Parvicella), and Lysobacter luteus sp. nov. (whose type strain is AS29MT=CECT 30171T=LMG 32343T).

Lysobacter chinensis sp. nov., a cellulose-degrading strain isolated from cow dung compost.

A novel bacterial strain, TLK-CK17T, was isolated from cow dung compost sample. The strain was Gram-staining negative, non-gliding rods, aerobic, and displayed growth at 15-40°C (optimally, 35°C), with 0-5.0% (w/v) NaCl (optimally, 0.5) and at pH 6.5-8.5 (optimally, 7.0-7.5). The assembled genome of strain TLK-CK17T has a total length of 4.3Mb with a G + C content of 68.2%. According to the genome analysis, strain TLK-CK17T encodes quite a few glycoside hydrolases that may play a role in the degradation of accumulated plant biomass in compost. On the basis 16S rRNA gene sequence analysis, strain TLK-CK17T showed the highest sequence similarity (98.9%) with L. penaei GDMCC 1.1817T, followed by L. maris KCTC 42381T (98.3%). Cells contained iso-C16:0, iso-C15:0, and summed feature 9 (comprising C17:1 ω9c and/or 10-methyl C16:0), as its major cellular fatty acids (> 10.0%) and ubiquinone-8 as the exclusively respiratory quinone. Diphosphatidylglycerol, phosphatidylethanolamine, and phosphatidylglycerol prevailed among phospholipids. Based on the phenotypic, genomic and phylogenetic data, strain TLK-CK17T represents a novel species of the genus Lysobacter, for which the name Lysobacter chinensis sp. nov. is proposed, and the type strain is TLK-CK17T (= CCTCC AB2021257T = KCTC 92122T).

Lysobacter ciconiae sp. nov., and Lysobacter avium sp. nov., isolated from the faeces of an Oriental stork.

Two Gram-stain-negative, mesophilic, strictly aerobic, nonspore forming, and yellow-pigmented strains with rod-shaped cells, designated H21R20T and H23M41T, were isolated from the faeces of an Oriental stork (Ciconia boyciana). Based on 16S rRNA gene sequences, both strains showed the highest similarity (98.3-98.4%) to the type strain of Lysobacter concretionis. Phylogenetic analysis based on the 16S rRNA genes and 92 bacterial core genes showed that strains H21R20T and H23M41T were robustly clustered with L. concretionis Ko07T. Whole genome sequencing revealed that the genomes of both strains were approximately 2.9 Mb in size. The DNA G + C contents of the H21R20T and H23M41T strains were 67.3 and 66.6%, respectively. The two strains showed 80.1-81.7% average nucleotide identity with L. concretionis Ko07T. Strain H21R20T grew optimally at 30°C and pH 8.0 and in the presence of 0.5-3% (wt/vol) NaCl, while strain H23M41T grew optimally at 30°C and pH 7.0-8.0 and in the presence of 0-3% (wt/vol) NaCl. Both strains possessed iso-C15:0, iso-C16:0 and summed feature 9 (iso-C17:1ω9c and/or C16:010-methyl) as the major cellular fatty acids, ubiquinone Q-8 as a predominant quinone, and diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine as the major polar lipids. A multifaceted investigation demonstrated that strains H21R20T and H23M41T represent novel species of the genus Lysobacter, for which we propose the names Lysobacter ciconiae sp. nov. and Lysobacter avium sp. nov. for strains H21R20T (= KCTC 82316T = JCM 34832T) and H23M41T (= KCTC 62676T = JCM 33223T), respectively.

Complete Genome Sequences of Two Lysobacter Strains, Isolated from Seawater ( Lysobacter caseinilyticus ) and Soil ( Lysobacter helvus ) in South Korea

ABSTRACTLysobacter species produce lysobactin, a depsipeptide antibiotic that is effective against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Staphylococcus aureus. Here, we report complete genome sequences of two Lysobacter strains, which were isolated from seawater (Lysobacter caseinilyticus) and soil (Lysobacter helvus) in South Korea.

Lysobacter arenosi sp. nov. and Lysobacter solisilvae sp. nov. isolated from soil.

Two Gram-stain negative, yellow-pigmented, and mesophilic bacteria, designated strains R7T and R19T, were isolated from sandy and forest soil, South Korea, respectively. Both strains were non-motile rods showing catalase- and oxidase-positive activities. Both strains were shown to grow at 10-37°C and pH 6.0-9.0, and in the presence of 0-1.5% (w/v) NaCl. Strain R7T contained iso-C14:0, iso-C15:0, iso-C16:0, and summed feature 9 (comprising C16:0 10-methyl and/or iso-C17:1ω9c), whereas strain R19T contained iso-C11:0 3-OH, C16:1ω7c alcohol, iso-C11:0, iso-C15:0, iso-C16:0, and summed feature 9 (comprising C16:0 10-methyl and/or iso-C17:1ω9c) as major cellular fatty acids (> 5%). Both strains contained ubiquin-one-8 as the sole isoprenoid quinone and phosphatidylglycerol, phosphatidylethanolamine, and an unidentified phospholipid as the major polar lipids. The DNA G + C contents of strains R7T and R19T calculated from their genomes were 66.9 mol% and 68.9 mol%, respectively. Strains R7T and R19T were most closely related to Lysobacter panacisoli C8-1T and Lysobacter niabensis GH34-4T with 98.7% and 97.8% 16S rRNA sequence similarities, respectively. Phylogenetic analyses based on 16S rRNA gene sequences showed that strains R7T and R19T formed distinct phylogenetic lineages within the genus Lysobacter. Based on phenotypic, chemotaxonomic, and molecular features, strains R7T and R19T represent novel species of the genus Lysobacter, for which the names Lysobacter arenosi sp. nov. and Lysobacter solisilvae sp. nov. are proposed. The type strains of L. arenosi and L. solisilvae are R7T (= KACC 21663T = JCM 34257T) and R19T (= KACC 21767T = JCM 34258T), respectively.

Characterization of Lysobacter spp. strains and their potential use as biocontrol agents against pear anthracnose

Colletotrichum fructicola, is an important fungal pathogen that has been reported to cause pear (Pyrus) anthracnose in China, resulting in substantial economic losses due to severe defoliation and decreased fruit quality and yield. In the search for novel strategies to control pear anthracnose, Lysobacter strains have drawn a great deal of attention due to their high-level production of extracellular enzymes and bioactive metabolites. In the present study, we compared four Lysobacter strains including Lysobacter enzymogenes OH11, Lysobacter antibioticus OH13, Lysobacter gummosus OH17 and Lysobacter brunescens OH23 with respect to their characteristics and activity against pear anthracnose caused by C. fructicola. The results showed that the evaluated Lysobacter species presented various colony morphologies when cultured on different media and were proficient in producing protease, chitinase, cellulase and glucanase, with L. enzymogenes OH11 showing typical twitching motility. L. enzymogenes OH11 and L. gummosus OH17 showed potent activity against the tested fungi and oomycetes. L. gummosus OH17 produced HSAF (heat-stable antifungal factor) which was demonstrated to be a major antifungal factor in L. enzymogenes OH11 and C3. Furthermore, L. antibioticus OH13 and L. brunescens OH23 exhibited strong antibacterial activity, especially against Xanthomonas species. Cultures of L. enzymogenes OH11 protected pear against anthracnose caused by C. fructicola, and the in vivo results indicated that treatment with an L. enzymogenes OH11 culture could decrease the diameter of lesions in pears by 35 % and reduce the severity of rot symptoms compared to that observed in the control. In the present study, we systemically compared four Lysobacter strains and demonstrated that they have strong antagonistic activity against a range of pathogens, demonstrating their promise in the development of biological control agents.

Lysobacter telluris sp. nov., isolated from Korean rhizosphere soil.

A Gram-stain-negative, aerobic, non-motile, non-spore-forming light-yellow-coloured rod-shaped bacterial strain, designated YJ15T, was isolated from soil at Bigeum island in Korea. Growth was observed at 10-37°C (optimum, 28°C), at pH 6.0-7.5 (optimum, pH 7.0) and in the absence of NaCl. Based on 16S rRNA gene sequence analysis, strain YJ15T was closely related to 'Lysobacter tongrenensis' YS037T (97.8%), Lysobacter pocheonensis Gsoil193T (96.5%) and Lysobacter daecheongensis Dae08T (95.8%) and phylogenetically grouped together with 'Lysobacter tongrenensis' YS037T, Lysobacter dokdonensis DS-58T and Lysobacter pocheonensis Gsoil 193T. The DNA-DNA relatedness between strain YJ15T and 'Lysobacter tongrenensis' KCTC 52206T was 12% and the phylogenomic analysis based on the whole genome sequence demonstrated that strain YJ20T formed a distinct phyletic line with Lysobacterlter dokdonensis DS-58T showing average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values of 76.3 and 21.3%, respectively. The predominant ubiquinone was identified as Q-8, and polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and two unidentified aminolipids. The major fatty acids were iso-C17:1 ω9c, iso-C15:0, iso-C16:0 and iso-C17:0. The genomic DNA G + C content was 68.2mol%. On the basis of phenotypic, chemotaxonomic properties and phylogenetic analyses in this study, strain YJ15T is considered to represent a novel species of the genus Lysobacter, for which the name Lysobacter telluris sp. nov. is proposed. The type strain is YJ15T (= KACC 19552T = NBRC 113197T).

Lysobacter prati sp. nov., isolated from a plateau meadow sample.

A novel proteobacterial strain designated SYSU H10001T was isolated from a soil sample collected from plateau meadow in Hongyuan county, Sichuan province, south-western China. The taxonomic position of the strain was investigated using a polyphasic approach. On the basis of 16S rRNA gene sequence similarities and phylogenetic analysis, strain SYSU H10001T was most closely related to Lysobacter soli KCTC 22011T (98.6%, sequence similarity) and Lysobacter panacisoli JCM 19212T (98.2%). The prediction result of secondary metabolites based on genome shown that the strain SYSU H10001T contained 3 clusters of bacteriocins, 1 cluster of non-ribosomal peptide synthetase, 1 cluster of type 1 polyketide synthase and 1 cluster of arylpolyene. In addition, the major isoprenoid quinone was Q-8 and the major fatty acids were identified as iso-C15:0, iso-C17:0 and Summed feature 9. The polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and three unidentified phospholipids. The genomic DNA G + C content of strain SYSU H10001T was 66.5% (genome). On the basis of phenotypic, genotypic and phylogenetic data, strain SYSU H10001T represents a novel species of the genus Lysobacter, for which the name Lysobacter prati sp. nov. is proposed. The type strain is SYSU H10001T (= KCTC 72062T = CGMCC 1.16662T).

The AHL Quorum-Sensing System Negatively Regulates Growth and Autolysis in Lysobacter brunescens.

Lysobacter species are emerging as novel sources of antibiotics, but the regulation of their physiological metabolism is still poorly understood. In this work, we extracted AHL (acyl-homoserine lactone) autoinducers, identified the structures of AHLs and described the AHL quorum-sensing system in Lysobacter brunescens OH23. AHLs were isolated from the supernatant of L. brunescens OH23, and ESI-MS/MS (electrospray ionization mass spectrometry) analysis revealed biosynthesis of three different AHL chemical structures by L. brunescens OH23: N-(3-oxohexanoyl)- homoserine lactone (HSL), 3-OH-C10-HSL and C8-HSL. The growth rate of AHL quorum-sensing knockout mutants was dramatically increased compared to that of wildtype. Sucrose consumptions were also twice as high in AHL quorum-sensing knockout mutants than that in wildtype in early-log phase. Additionally, expression of key genes related to sucrose metabolism α-glucosidase was enhanced in AHL quorum-sensing knockout mutants, which indicated that AHL quorum sensing negatively regulates sucrose uptake and metabolism which further affects the growth rate of L. brunescens. Furthermore, autolysis was strongly induced in AHL quorum-sensing knockout mutants compared to wildtype, suggesting that AHL quorum sensing plays a negative regulatory role in cell autolysis. Moreover, compared to wildtype, XSAC (Xanthomonas-specific antibiotic compound) production was significantly increased in AHL knockout mutants in the early-log and late-log phases, and surface motility capabilities are also enhanced also in AHL knockout mutants; the normalized data of XSAC production and surface motility and expressions of key genes related to these two phenotypes reveal that growth rare and autolysis strongly affects XSAC biosynthesis and surface motility rather than AHL quorum-sensing system. Our results show that the AHL quorum-sensing system negatively regulates cell growth and autolysis, and further maintain nutrition homeostasis and population stability in L. brunescens.

Lysobacter terrigena sp. nov., isolated from a Korean soil sample.

A bacterial strain isolated from a soil collected in Jeju Island, designated as 17J7-1T, was Gram-negative, rod-shaped, yellow colored, and motile by gliding. This strain was able to grow at temperature range from 10 to 42°C, pH 7-9, and tolerated up to 1% NaCl. Analysis of 16S rRNA sequence identified strain 17J7-1T as a member of the genus Lysobacter with close sequence similarity with Lysobacter mobilis 9NM-14T (97.4%), Lysobacter xinjiangensis RCML-52T (97.0%), and Lysobacter humi FJY8T (96.9%). The genomic DNA G + C content of the isolate was 67.9mol%. DNA-DNA relatedness between strain 17J7-1T and L. mobilis, L. humi, and L. xinjiangensis were 42.3%, 39.5%, and 35.8%, respectively, clearly showing that the isolate is distinct from its closest phylogenetic neighbors in the genus Lysobacter. Average nucleotide identity (ANI) and digital DNA-DNAhybridization (dDDH) values between strain 17J7-1T and L. enzymogenes ATCC 29487T, the type species of this genus, and several other close Lysobacter species were less than 77% and 22%, respectively. Major fatty acids were C16:0 iso (29.8%), summed feature 9 (C17:1 iso ω9c/C16:0 10-methyl; 20.1%), and C15:0 iso (17.7%). The predominant respiratory quinone was ubiquinone Q-8 and the major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol. In the light of the polyphasic evidence accumulated in this study, strain 17J7-1T is considered to represent a novel species in the genus Lysobacter, for which name Lysobacter terrigena sp. nov. is proposed. The type strain is 17J7-1T (= KCTC 62217T = JCM 33057T).

Lysobacter segetis sp. nov., Isolated from Soil.

A Gram-negative, aerobic, motile by gliding, rod-shaped bacterium, strain 17J68-2T, was isolated from a soil sample taken from Jeju Island, Republic of Korea. The isolate displayed high 16S rRNA gene sequence similarity to the members of the genus Lysobacter in the family Lysobacteraceae, with Lysobacter humi FJY8T (98.4% similarity), Lysobacter xinjiangensis RCML-52T (98.3%), and Lysobacter mobilis 9NM-14T (98.1%) as closest phylogenetic neighbors. Growth of strain 17J68-2T occurred at 15-42°C, pH 7-8, and in the presence of 0-1.0% NaCl. Draft genome was 2.94Mb in size with G+C content of 70.5mol%. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, and phosphatidylethanolamine. Ubiquinone Q-8 was the predominant respiratory quinone and the major fatty acids were C16:0 iso (39.4%), summed feature 3 (C16:1ω7c/C16:1ω6c) (6.6%), C11:0 iso 3-OH (6.4%), C15:0 iso (6.4%), and C16:1 iso H (6.2%). The DNA-DNA relatedness between strain 17J68-2T and L. humi, L. xinjiangensis, and L. mobilis were 39.9, 39.4, and 25.3%, respectively. From these results, it is concluded that the novel isolate possesses sufficient characteristics to differentiate it from the most closely affiliated Lysobacter species, and strain 17J68-2T represents a novel species of the genus Lysobacter, for which the name Lysobacter segetis sp. nov. (=KCTC 62237T = JCM 33058T) is proposed.